Month: October 2012

NYC has not, thankfully, rolled snake-eyes here…it’s going to be a very bad storm when it’s all tallied for the NYC area, but an impact over Atlantic City is mercifully just far enough south that it may blunt the wind damage aspect of the storm. The surge is the real worry for everyone in a coastal community…but I just wanted to let everyone know that I believe we’re catching a bit of a break.

I will however, send my prayers out to the Jersey shore in the hope that no lives are lost.

This morning, the central pressure inside Hurricane Sandy – rapidly losing tropical characteristics in satellite appearance and seeing its wind field expand, but maintaining a visible warm core aloft – has fallen to 951 mb. It is slowly gaining strength and will continue to do so until near the point where it reaches a landfall that should occur somewhere near or just south of Sandy Hook, NJ. Which implies that our forecasts of a storm with a 950-960 mb central pressure at landfall time were underdone.

Folks…getting hit by a 945 or even 935 mb storm is no laughing matter. This will be my last forecast update on this evolving blockbuster storm, as I will now spend the rest of my time in the modern world with electrical power doing the important things that need to be done. I recommend you do the same.

I am getting word that the Hurricane Center intends to stop issuing advisories on the storm after it gets north of North Carolina, claiming it is extra-tropical and not their concern. I am here to issue a stern warning to you and to EXCORIATE the Hurricane Center for using scientific minutia to avoid responsibility in a complex situation. Make excuses about it not being TECHNICALLY tropical anymore all you want..your bullshit is transparent and I’m not listening. SHAME on the Hurricane Center. SHAME on them for abandoning the people to confusion and forcing the Weather Service to do all the work and rouse the people to prepare properly for what could be a historic event.

Whether it has a symmetric, warm core or not…whether it’s over tropical waters or not…whether it looks more like a nor’easter or a hurricane…NO ONE GIVES A SHIT. The science can wait. You can reclassify it as extratropical for the geeks who write case-study papers two months from now (like me…heh) – but for right now, all that matters is the public and their safety and preparedness. It is a known fact that the public UNDERSTANDS what a Hurricane Warning means. Are they going to understand what a Coastal Flood Warning, Hurricane Force Wind Warning, Flood Watch, Rip Tide Warning etc all combine to mean? No…sorry…people don’t pay enough attention to realize that the difference between a hybrid nor’easter with tropical qualities and a hurricane is NOTHING in terms of impacts. No matter how NWS words their advisories and public information statements, they’re never going to have the same impact on boaters, coastal communities and the population at large as the NHC’s hurricane warning has. And evacuations get triggered automatically with hurricane warnings that may go un-ordered in the alternative scenario.

NHC forecasters know this. They KNOW that if they don’t issue dubious warnings, people aren’t going to act in the same way they would with them doing their god-damned jobs. If they fail to issue hurricane warnings, they are guilty of NEGLIGENT HOMICIDE if anyone dies because they did not prepare. You do not abandon the people to scientific jargon that means NOTHING to public lives and property. If it was at any time a hurricane, and it is having hurricane impacts…call it a f***ing hurricane and issue the damned warnings. Reclassifying it later for the eggheads if you must cling to your rules, but for now…do your damned jobs and protect our lives. Period.

On another matter, I am asking anyone who reads this to kindly IGNORE the NHC forecast. It’s absolute crap. They’re basing their track forecast on outdated, scientifically dubious, and frequently VERY wrong computer models that use techniques no longer considered the gold standard in mesoscale modeling – the GFDL and HWRF models they seem to obsessively lean on for predicting hurricane tracks are failing miserably compared to real time verifications of the NAM and GFS (and SREF guidance and EC and CMC and NOGAPS and even UKMet!!)…they have PERSISTENTLY been too far SW, too strong, and too broad with their circulations inside the storm and they are NOTORIOUS for those biases among weather forecasters. ALL MODEL GUIDANCE except for the models used primarily by the NHC are taking the storm in near Sandy Hook, NYC, or Central Jersey and NOT DOVER FRACKIN’ DELAWARE!

Their lack of competence is astounding…and their moral cowardice even more shocking.

Model agreement has improved…I’m not going to rehash the impacts I have discussed in previous posts except to say that with many of the western outliars now coming into line with a track that takes Sandy/FrankenStorm ashore near Sandy Hook, NJ, rather than the Delmarva or Atlantic City (or Cape Code on the other side, also now in the vast minority among solutions produced by the models), my confidence in the catastrophic impacts has increased still further.

A reminder, I defined a catstrophic event as one which produced 10 billion dollars in damage (or more, obviously) and I now believe this to be 90% likely. With a 100% chance of an east coast landfall somewhere between Cape May, NJ and Montawk, NY.

Provisions are being procured by everyone in my department here in Stony Brook – myself included. Prepare for the worst if you’re affected.

The DC readers will probably like to know that the wind forecast I made there holds, with a slight reduction in projected rainfall – I’m thinking 4-8 inches of rain are in the cards (in line with the rain the region got when Hurricane Fran hit NC in 1996.

With apologies to Steve Sisco of the HPC who coined the term in passing and is now getting credit for the hilarious name all over the interwebs.

Hurricane Sandy is beginning to acquire a post-tropical look in satellite presentations due to SSW wind shear aloft (which is expected to weaken after tomorrow afternoon) and some dry air from Mexican high plateau (which is temporarily feeding into the storm from the SW), but it still has a full warm core and a closed circulation, and will thus remain tropical for some time. It has, for the time being, weakened a touch to a 80 mph category 1 storm and is expected to weaken still further in the next day or two as it lifts NWW and then NE, strafing North Carolina with heavy rain and wind before stalling over the Gulf Stream. While near NC, it may regain a bit of strength or it may remain a category one hurricane, but don’t be fooled. The real trouble begins as it feels the effects of the approaching arctic trough.

Models have converged some over the last day of forecast cycles with only the ECMWF/NOGAPS (European/US Navy) insisting on a southern track that takes the storm closer to DC and Baltimore and only the CMC (Canadian) taking the storm far enough north to blunt the damaging impacts a bit. The SREF (short range ensemble forecast), NAM (North American Mesoscale), UKMet and GFS (US Medium Range) take the storm near or over Long Island.

If the core consensus among US generated models is any indication, and the storm really does track from off Hatteras to off Montawk, to NY Bight, or even just south of there as many of the SREF members are suggesting, it spells utter and complete disaster for NY City. A description of the likely impacts:

Subways flooded as storm surge exceeds 8 feet in the bight and on the batteries. Lower Manhattan under water.

Long Island’s beaches take a pounding, as to those in S CT, RI and MA and in NJ. Many areas lose multiple feet of beach and storm surges in some places exceed 10 feet.

Prolonged sustained winds to 50 mph begin late Sunday and last through early Tuesday with peak sustained winds of over 60 mph over much of Long Island and coastal New jersey. Gusts reach 90 mph in convective/heavy rainfall. Wind damage to trees, power lines and even windows in the city creates power outages and injures many.

Excessive rainfall, especially in New Jersey and Long Island, floods the traditionally prone areas very quickly.

Heavy SNOW! impacts the high terrain of the Adirondacks and Catskills in NY and Shenandoah (far W VA, WV, and PA) as the storm winds down and cools at all levels. With leaves still on the trees in many of these places, this could lead to tree damage.

Tornado impacts east of the track with such severe temperature contrasts and such explosively favorable dynamics aloft could be greater than normal for a tropical impact.

The saving grace is that this thing will not have the staying power of the Perfect Storm. That beast hammered the coasts while staying just offshore and holding its intensity for nearly 3 days. This will begin impacting our coasts Sunday and by Tuesday afternoon it will be weakening rapidly and the winds will by dying down.

Nonetheless, I now believe the probability of 10-digit (> 10 billion dollar) damage now exceeds 70% and the probability of a coastal impact is now near 100%. So…batten down the hatches. And hope your power doesn’t go out for longer than a few days. Hope…because that might actually be unlikely.

For the DC/VA readership here, I would just point out that there are now a few models out there trying to push this storm well SW of the consensus…it’s possible that the endgame could look a little like Hurricane Isabel (2003) with a track skirting Hatteras and then turning NW into the mouth of the Chesapeake and on into Charlottesville, VA…which would be a whole new kind of badness for the Chesapeake region and the DC metro area.

I may have written off the southern solutions prematurely. Though I still think this course is unlikely.

On the potential for an east coast tropical hybrid cyclone impact early next week, I can now raise the odds to 60%. A 10-digit damage event (10 billion or greater) carries odds of at least 30% as of this morning (10/25). The models have remained remarkably consistent in their bent-back track solutions as the various upper atmospheric features now come into alignment and appear over our instrument networks. As climatologically improbable as this event is, and as delicate the balances must be for it to take this deadly track to the NW after it passes Hatteras, I still cannot rule out a near miss or total escape, but those odds are dwindling.

To recap:

Hurricane Sandy – which is now a rapidly intensifying category 2 storm with central pressure of 964 mb – is confidently forecast to head north or NNE across Cuba and the Bahamas, and then turn NNW toward the Carolina coast tomorrow (Friday). It is then forecast to gently turn northeastward and slow WAY down to a near stall as a deep shortwave trough over the Northern Plains drops southeast and carves out a major east coast long wave trough. This larger trough – highly anomalous for this time of year – will work in conjunction with a strengthening area of high pressure south of Greenland to trap Sandy and turn it northward again early Saturday. From this point, little is known about the final trajectory of the storm, but all current operational guidance agrees on a few points:

The storm will begin undergoing a transition from tropical cyclone to hybrid nor’easter on Sunday – the exact timing of this transition is still open for speculation.

As its core cools, it will feel the influence of the approaching east coast trough more strongly and begin to turn NW or even WNW on Sunday Night or Monday. The timing of this westward bend in its track is absolutely crucial – too early and it makes landfall (and begins weakening slowly) over south Jersey or the DelMarVa Peninsula, too late and the turn takes it into the Canadian maritimes as a weaker, more sheared system and everyone breathes a sigh of relief.

At its most intense (and generally, the peak intensity is forecast to be near its time of landfall!), the storm is forecast to have central pressures of between 942 and 965 mb. The October 31, 1991 “Perfect Storm” which appeared on the silver screen had a peak central pressure of 969 mb.

Its wind field will be MASSIVE – tropical storm force sustained winds potentially extending 500 km from the center of circulation – especially east of the track.

25-50 foot swells, 6-10 foot storm surges, and hurricane force sustained winds are entirely possible as it comes ashore, and unlike a fully tropical system (say, Hurricane Irene) these conditions will occur well inland. Tropical systems lose their low level wind field due to friction and increased static stability near the ground. Extratropical cyclones are cool cored, and thus unstable through the air column, meaning high flight-level winds may mix to the ground more effectively over a large part of the NE US.

As noted, this landfall could occur as far east as Halifax, NS CA and as far west as Cape May, NJ or even Salisbury, MD, but I believe the most likely impact is from Sandy Hook, NJ (south of NY Bight) to Kiterie, ME. If indeed the storm makes landfall in my highest risk area (I’d say there’s a good 30% chance of that), it will be one of the worst storms in New England’s long recorded history…and I won’t be on Long Island to see it…I’ll have bugged out for my fiance’s home in Lexington, MA, where at least storm surge flooding and isolation due to structural failure of the transportation network will be less of a threat.

Continuing my commentary on the potential for a major east coast weather disaster, I thought I would add a few points of clarification and a comment about the at risk areas:

First, on those pesky computer models and the reasons for the uncertainty with this storm:

Even in models which produce the big storm, the result stands on a razor’s edge. Everything hinges on how far SE and how intense the arriving short wave that should be approaching the Appalachians by Sunday evening can get and how quickly it gets there. A little too fast, and it boots the hurricane out to sea before it has a chance to undergo extratropical transition, meaning the threat would shift toward Bermuda and then possibly the Canadian Maritimes. To slow, and the trough doesn’t acquire the depth and sharpness needed to pull the storm back toward the coast and it moves harmlessly offshore, giving us a light brush and some nasty surf. Even slower, and the storm actually has an opening to make landfall in the Carolinas, though this is unlikely. On top of that, the precise intensity of the storm will help to shape the blocking ridge in its path and also to pull in energy from the west. A stronger storm could expedite the deepening of the trough over the east and build the block further, leading to a westward path. A weaker storm would most likely never come close to land.

By no means do all of the models get this storm onto land. The ensemble of global predictions is placing more emphasis on the western solutions at the moment, but not all of the players are on the field for this high stakes game, so it’s too early to claim model consensus.

Our models VERY poor at capturing the move from tropical to extratropical cyclone and getting the thermal structure of the storm right. And in this case, how warm the system is aloft could be hugely important to its track.

Now…Folks who should and should not be worried:

The current threat is to Florida, where very high seas and tropical storm conditions will continue for the next couple of days. Those outer bands of heavy rains and squally winds will impact the Carolina coasts as well as we head into Friday and Saturday.

The threat for a big news maker is north of a line from Norfolk to Baltimore to Pittsburgh to Detroit…it is not likely to be a big deal in DC or Richmond as it would be exceedingly rare for a system to cut back that far west that quickly this late in the tropical season.

The threat for a catastrophic solution is centered around Long Island and New York City…if it does not hook back to the west until it is further north, it would likely be a weaker storm as it would be dealing with a lot of wind shear before properly phasing with the polar jet stream. If it hooks west too early, the coast line is not shaped in such a way as to merit a ton of concern about catastrophic surge. But it if comes ashore over Long Island of Coastal New Jersey, the surge, wind and flood damage could be history-making and cost billions of dollars, because these are the tracks that favor the strongest low and the most unfriendly coastal morphology. A 6 foot surge will flood the subway tunnels in NYC…this storm could easily top those levels if it comes far enough west.